Conventional navigation systems are usually mounted in mobile objects such as a vehicle, a vessel, an airplane and the like, so as to detect a current position, a proceeding direction and a speed thereof.
The conventional navigation system detects the current position of a mobile object based on GPS (global positioning system) signals indicating information on longitude, latitude, and altitude thereof, which are received from a plurality of satellites, and displays the detected current position of the object on a map visualized through a display device. The navigation system also searches for a navigation path, i.e., a short-cut path or an optimum path from a departure point to a destination, and display the navigation path on the map visualized through the display device.
FIG. 1 is a flow chart showing a conventional method for controlling a navigation system. In case a vehicle deviates from a navigation path, the navigation system operates as follows.
After the navigation system receives a command signal to detect a navigation path, the signal being inputted by a driver, the navigation system transmits the signal to a path detecting server via a wireless network (S 10). Then, the path detecting server figures out the navigation path by using a route planning method to thereby provide path data, which represents the navigation path, to the navigation system via the wireless network (S 20).
The navigation system displays the navigation path on a screen such as an LCD and the like in response to the path data (S 30).
A navigation sensor unit included in the navigation system detects a present position of the vehicle in the course of displaying the navigation path (S 40).
The navigation system determines whether the present position of the vehicle deviates from the navigation path or not (S 50). When the present position of the vehicle deviates from the navigation path, the navigation system sends a signal demanding a detection of a revised navigation path to the path detecting server (S 60).
Subsequently, the path detecting server figures out the revised navigation path required by the navigation system. Herein, the revised navigation path means a new navigation path from a deviation point to the destination (S 70), wherein the deviation point is a place where the vehicle begins to deviate from the navigation path.
Thereafter, the path detecting server transmits revised path data, which indicates the revised navigation path, to the navigation system via the wireless network. Then, the navigation system displays the revised navigation path in response to the revised path data (S 30).
However, in step 50, if the vehicle is determined to continue to travel along the original navigation path, the navigation system determines whether the vehicle has arrived at the destination or not (S 80).
If the vehicle has arrived at the destination, the operation of the navigation system is completed (S 90); otherwise, the navigation system returns to step 30 to display the navigation path.
As mentioned above, when the vehicle deviates from the original navigation path, the conventional navigation system does not inform the driver of a revised navigation path until the navigation system demands a detection of the revised navigation path to the path detecting server and then receives the revised path data from the path detecting server. Therefore, there is a time delay problem in finding the revised navigation path.